Random orbital sander

ABSTRACT

There is disclosed in connection with a random orbital sander the utilization of improved arrangements for resiliently supporting an air motor, controlling the flow of pressurized air to the motor, and utilizing air exhausted from the motor to withdraw dust from a shroud arranged to collect dust generated incident to operation of the sander. Also disclosed is an alternative dust collecting arrangement, wherein the shroud is connected by a sander mounted duct to a source of vacuum.

BACKGROUND OF THE INVENTION

Pneumatically operated power tools, such as sanders, are typicallyformed with a cast or molded housing having a chamber for receiving anair powered motor, air supply and discharge passageways communicatingwith the chamber through an annular side wall thereof for supplying airto and exhausting air from air supply and discharge ports of the motor,and a chamber for receiving a manually operated valve adapted to controlflow of air through the air supply passageway.

In accordance with standard housing casting or molding practice, it isnecessary to provide a relief for the side walls of chambers in order topermit withdrawal of chamber forming inserts from the housing at thecompletion of the casting or molding operation. It has been typicalmanufacturing practice to bore out motor receiving chambers to removethe relief and accurately size such chambers to frictionally receive acylindrical side wall of the casing of the motor through which its airsupply and exhaust ports extend. A relatively tight fit was required tobe provided between the facing side walls of the chamber and motorcasing in order to prevent leakage of air annularly within the chamberbetween the air supply and discharge passageways, and this added greatlyto the cost of housing manufacture and motor assembly. An added drawbackof this prior manufacturing practice is that vibrations of the motorand/or tool with which it is connected are transferred directly to thehousing and from the housing to the operator of the tool.

It has been proposed to resiliently mount air motors within the chamberof an air powered tool by providing a pair of resiliently deformablebands adapted to encircle opposite ends of the motor casing, but in suchinstallations revised motor casing and housing structures are requiredto permit at least one of the air supply and discharge ports of themotor casing to open axially thereof and at least one of the air supplyand discharge passages to open into the chamber in an axial direction.

As with the case of motor receiving chambers, it has been commonpractice to bore out the valve receiving chambers of air tools toprovide for a proper fit with cylindrical rotary valve sleeves, andagain this adds to the cost of housing manufacture and valveinstallation. Another drawback of standard rotary valve constructionsemployed in air power tools is that they provide for non-linearadjustments of air flow in which slight rotational movements of thevalve result in large changes in air flow. As a result, fine adjustmentsof air flow are difficult for a tool operator to achieve.

Further, various attempts have been made to provide air powered tools,such as sanders, with diverse dust collecting devices. However, priordevices of which we are aware have various disadvantages, which eitherresult in increased tool costs or inefficiencies in the dust collectionoperation.

SUMMARY OF THE INVENTION

The present invention relates to improvements adapted for use withpneumatically powered tools and particularly adapted for use with tools,such as random orbital sanders, wherein dust is generated as an incidentto operation of such tools.

A first aspect of the present invention involves the provision of anarrangement for both resiliently mounting an air powered motor within achamber of a tool housing and fluid sealing an air inlet port of acasing of the motor and an air supply passageway of the housing relativeto an air exhaust port of the motor casing and an air supply passagewayof the housing for a tool construction wherein the ports and passagewaysopen through facing wall surfaces of the motor casing and housingchamber. Preferably, the arrangement includes a pair of separatelyformed, resiliently deformable parts engaging about opposite ends of themotor casing and having integrally formed pairs of sealing projectionsextending from the parts with the free ends of the projections beingengageable to provide seals spaced annularly of the facing wall surfacesof the motor casing and housing chamber and to positionally locate theparts relative to one another. The invention permits mounting of themotor within a chamber of a cast or mold formed tool housing withoutaltering the as-formed frusto-conical configuration of the chamber tocorrespond to the shape of the side wall of the motor casing.

A second aspect of the invention involves the provision of a uniquelyconstructed, pressurized air flow control valve for an air tool allowingfor a substantially more linear control of air flow through the toolthan achievable with prior rotary type flow control valves of which weare aware.

A third aspect of the invention involves an arrangement for collectingdust generated incident to operation of a tool, such as a sander,wherein a dust collecting shroud is connected to a remote vacuum sourceby a duct removably mounted on a housing of the tool by a mufflerthrough which air is exhausted from the tool.

A fourth aspect of the invention involves an arrangement for collectingdust generated incident to operation of an air powered tool, such as asander, wherein a dust collecting shroud is arranged in flowcommunication with a reduced pressure air stream created by anaspirator, which is removably mounted on a housing of the tool andsupplied with air exhausted from the tool.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature and mode of operation of the present invention will now bemore fully described in the following detailed description taken withthe accompanying drawings wherein:

FIG. 1 is a side elevational view of a pneumatically operated, randomorbital sander incorporating the present invention;

FIG. 2 is a top plan view thereof;

FIG. 3 is a sectional view taken generally along line the 3--3 in FIG.2;

FIG. 4 is a sectional view taken generally along line the 4--4 in FIG.1;

FIG. 5 is an exploded perspective view showing a pneumatic motorincorporated in the sander and resilient support thereof;

FIG. 6 is an exploded sectional view taken generally along the line 6--6in FIG. 2;

FIG. 7 is a sectional view taken generally along the line 7--7 in FIG.3;

FIG. 8 is an exploded perspective view of a dust collecting arrangement;

FIG. 9 is a sectional view of the dust collecting arrangement of FIG. 8in assembled condition;

FIG. 10 is a sectional view taken generally along the line 10--10 inFIG. 9;

FIG. 11 is an exploded perspective view showing a further dustcollecting arrangement;

FIG. 12 is a sectional view of the dust collecting arrangement of FIG.11 in assembled condition;

FIG. 13 is an enlarged sectional view taken generally along the line13--13 in FIG. 12;

FIG. 14 is an enlarged sectional view taken generally along the line14--14 in FIG. 13; and

FIG. 15 is an enlarged sectional view taken generally along the line16--16 in FIG. 12.

DETAILED DESCRIPTION

The present invention will now be described for example as beingincorporated in a pneumatically driven random orbital sander generallydesignated as 10 in FIGS. 1-4.

Random orbital sanders typically include a cast or molded housing 12defining a chamber 14 having a side or boundary wall 16 extendingbetween inner and open outer ends 18 and 20 of the chamber; an air inletor supply passageway 22 opening through the chamber side wall forsupplying pressurized air to the chamber from a suitable source, notshown, under the control of a flow control valve 24 manually operable bya housing mounted lever 26; and an air outlet or discharge passageway 28opening through the chamber side wall for placing the chamber incommunication with the atmosphere via a suitable noise suppressingmuffler assembly 30. Mounted within chamber 14 is a pneumatic motor 32shown generally in FIGS. 3, 4 and 5 as including a motor casing 34having a side wall portion 34a and opposite or inner wall and outer endwall portions 34b and 34c, which cooperate to define an eccentricallylocated rotor chamber 36 having air inlet or supply and exhaust ordischarge ports 38 and 40, respectively, which open radially through thecylindrical outer surface 42 of side wall portion 34a at points spacedannularly thereof for flow communication with the housing air inlet andoutlet passageways, respectively; a rotor 44 supported within the rotorchamber by a motor drive shaft 46 whose outwardly projecting or oppositeends are in turn rotatably supported by bearings 48; and a plurality ofrotor vanes 50 slidably carried by the rotor for movement radially ofthe motor drive shaft. Motor 32 may be retained within chamber 14 by asuitable clamping ring device 20a. Motor drive shaft 46 is coupled via arandom orbital drive connection 52 to a suitable sanding disc 54, and ashroud 56 is carried by housing 12 in close proximity to sanding pad 54.The construction of sander 10, as thus far generally described, isconventional.

In accordance with the preferred form of the present invention, thebasic construction of sander 10 is modified in respect to theconstruction and mode of mounting flow control valve 24. Valve 24 isshown in FIGS. 3 and 4 as generally including an axially elongated valvesleeve 58 rotatably received within an open ended valve chamber 60formed in housing 12 and arranged to extend transversely of and in flowcommunication with inlet passageway 22, such that the latter is dividedinto a stepped diameter inlet path 22a and an outlet path 22b; a valveseat defined by a washer 62 mounted within inlet path 22a; a valvemember 64; a valve member biasing spring 66; and an operator 68.

Valve sleeve 58 is mold formed to provide a transversely extendingthrough opening 70 having its inlet and outlet ends 70a and 70b arrangedfor flow communication with the outlet end of flow path 22a and theinlet end of flow path 22b, respectively; an axially extending boreopening 72, which extends through an upper end of the valve sleeve, asviewed in FIG. 3, for communication with through opening 70, and servesto rotatably and slidably support operator 68 intermediate the endsthereof; an enlarged lower end 74 arranged exteriorly of valve chamber60 for use in manually imparting rotations to the valve sleeve withinthe valve chamber between first and second limits to be described; apair of annular recesses vertically bounding the through opening forreceiving O-ring seals 76; and an upper annular recess for receiving aC-shaped snap ring 78, which cooperates with lower end 74 to removablyretain the valve sleeve within the valve chamber.

Preferably, valve chamber 60 is permitted to retain an as-formedfrusto-conical configuration, wherein its upper end is of smallerdiameter than its lower end, as viewed in FIG. 3, which results from therequirement for providing a small relief to facilitate withdrawal of avalve chamber forming mold insert from housing 12 at the completion ofits casting or mold forming operation. Valve sleeve 58 is mold formedsuch that its side surface is frusto-conical and has a reliefcorresponding to the relief of valve chamber 60 in order to facilitateinsertion of the valve sleeve and 0-ring seals 76 upwardly into thevalve chamber.

Valve member 64 is formed with a sealing end in the form of a valve disc64a normally maintained in surface-to-surface sealing engagement withwasher 62 by spring 66 and an operating end in the form of a pin shaftor stem 64b, which is fixed to disc 64a and extends freely throughwasher 62 and into through opening 70 via inlet end 70a for pivotalconnection with the lower or inner end of operator 68, such as may beprovided by forming the lower end of the operator with a slot opening,not shown, sized to loosely receive pin shaft 64b. The upper or outerend of operator 68 is arranged to underengage lever 26.

Be referring to FIG. 3, it will be understood that spring 66 normallyserves to maintain valve disc 64a seated against washer 62 in order toblock flow of air through inlet passageway 22. As an incident to theseating of valve disc 64a, pin shaft 64b forces operator 68 into itsillustrated outwardly extended position. When it is desired to operatesander 10, lever 26 is squeezed or manually depressed, thereby forcingoperator 68 to move inwardly of valve sleeve 58 to effect tilting ofvalve member 64 against the bias of spring 66 sufficiently to unseatvalve disc 64a in order to place path 22a in flow communication withpath 22b via through opening 70.

The first and second limits of rotational movement of valve sleeve 58mentioned above are preferably defined by alternative engagement by apair of abutment surfaces, not shown, defined by enlarged lower end 74with a fixed abutment, also not shown, formed integrally with housing12. Valve sleeve 58 is shown as being in its first limited rotationalposition in FIGS. 3, 4 and 7, wherein through opening inlet end 70a isdisposed in unobstructed or full flow communication with the outlet ofpath 22a and through opening outlet end 70b is in unobstructed or fullflow communication with the inlet of path 22b, thereby to provide for agiven maximum flow of air through passageway 22 into chamber 14 whenevervalve disc 64a is unseated. By manual manipulation of enlarged lower end74, valve sleeve 58 may be rotated in the direction indicated by arrow84 in FIG. 4 into its second limited rotational position shown in brokenline in FIG. 7, wherein through opening outlet end 70b is annularlydisplaced relative to the inlet of path 22b, thereby to partially blocksuch inlet and reduce flow of air into chamber 14 to some given minimumvalue. During rotation of valve sleeve 58 into its second limitedrotational position, through opening inlet end 70a remains inunobstructed flow communication with the outlet of path 22a in that suchinlet end is required to be relatively large, as shown in FIG. 4, inorder to permit rotation of the valve sleeve between its first andsecond positions without its engaging with pin shaft 64b.

In a presently preferred construction shown in FIG. 7, through openingoutlet end 70b is bounded in part by an essentially straight boundaryedge 70b' which is inclined relative to the direction of rotation ofvalve sleeve 58, the inlet of path 22b is of circular cross-sectionalconfiguration, and the boundary edge is arranged to sweep across theinlet of flow path, as valve sleeve 58 is rotated from its first intoits second limited rotational position. This construction provides for asubstantial more linear variation in the flow of air into the inlet ofpath 22b than would occur if outlet end 70b were of circularcross-sectional configuration, as is common in rotor flow controlvalves. The extent of the adjustment of air flow depends upon the extentof rotational displacement of valve sleeve 58 and the length andinclination of boundary edge 70b'.

Further in accordance with the preferred form of the present invention,there is provided a unique arrangement for both resiliently mountingmotor 32 within housing chamber 14 and fluid sealing air supplypassageway 22 and motor inlet port 38 from air outlet passageway 28 andmotor exhaust port 40. More specifically, reference is made to FIGS. 3,4 and 5, wherein resiliently deformable means for supporting and fluidsealing motor 32 within and relative to chamber 14 is shown as includingfirst and second mounting portions 88 and 90, which peripherally engagewith the relatively inner and outer ends of motor casing 34, and a pairof intermediate sealing portions 92a and 92b, which extend between themounting portions.

As shown in FIGS. 3, 4 and 5, mounting end portions 88 and 90 are in theform of end caps having annular side portions 88a and 90a, which bridgeacross the joints between motor casing side wall portion 34a and endwall portions 34b and 34c and extend radially between casing 34 andchamber side wall 16 thereby to peripherally fluid seal the motor casingrelative to the chamber side wall adjacent chamber opposite ends 18 and20; and washer-shaped end portions 88b and 90b, which overlie the outeror oppositely facing surfaces of casing end wall portions 34b and 34cand fluid seal same relative to chamber inner end 18 and a motor clampring device 20a. As best shown in FIG. 4, sealing portions 92a and 92bextend radially between casing side wall portion 34a and chamber sidewall 16 to provide a fluid seal therebetween, and are annularly spacedapart through 180° and arranged to annularly separate or fluid seal airsupply passageway 22 and air supply port 38 from air exhaust 28 and airdischarge port 40.

Preferably, the resiliently deformable means is formed of separate firstand second parts shown in FIG. 5 as defining first and second mountingportions 88 and 90 from which extend integrally formed pairs of sealingprojections 94a, 94b and 96a, 96b, which are adapted to cooperate todefine sealing portions 92a and 92b. Sealing projections 94a, 94b and96a, 96b have free ends of generally saw tooth shaped configuration,which are intended to interengage in order to positionally locatemounting portions 88 and 90 relative to one another with the respectivepairs of sealing projections disposed in alignment, provide a fluid sealbetween the ends of the sealing projections, and prevent relativerotation between the mounting portions about the lengthwise extendingaxis of casing 34. As shown in FIGS. 3 and 5, mounting portion 88 isadapted to be positionally located and constrained against rotationrelative to casing 34 by providing end wall portion 88b with an opening98 sized to slidably receive a casing carried mounting pin 100. Casing34 is in turn positionally located and constrained against rotationrelative to chamber 14 by inserting the free end of mounting pin 100into a recess 102 formed as a part of housing 12 adjacent chamber innerend 18.

Preferably, as with the case of valve chamber 60, chamber 14 ispermitted to retain its as-formed frusto-conical configuration, whereinside wall 16 has a slightly larger diameter adjacent chamber outer end20 than adjacent chamber inner end 18. When shrinkage problems occurduring mold forming of housing 12 resulting in side wall 16 beingimproperly formed, chamber 14 may be formed undersized and then machinedto define the side wall. When chamber side wall 16 is of frusto-conicalconfiguration, it is preferable to mold form mounting portions 88 and 90such that their outer surfaces have a relief corresponding to the reliefof chamber side wall 16 in order to facilitate insertion of motor 32 andits mounting portions into cavity 14.

In order to facilitate initiation of rotation of rotor 44, casing endwall portions 34b and 34c are provided with additional air inlet ports38', and this requires annular end portions 88a and 90a to be providedwith notches or cutouts 88a' and 90a' aligned therewith.

Muffler assembly 30 is shown in FIGS. 4 and 6 as including a mufflerbody 104, which serves to mount the muffler assembly on housing 12 inassociation with an enlarged, partially screw threaded outlet end 28a ofair outlet passageway 28; a muffler cone 106 of molded porous metalconstruction; a muffler end cap 108; and a muffler end cap insert 110 offibrous material. Muffler body 104 is in the general form of a sleevehaving an outer surface formed with a first or assembly mounting end104a threaded for removable mounting within passageway outlet end 28a, agenerally cylindrical second or muffler cap mounting end 104b formedwith a plurality of upstanding mounting tabs 104b' and an intermediateradially outwardly extending annular abutment flange 104c; and an innersurface formed with a cylindrically shaped first end 104d sized tofrictionally receive muffler cone 106, a non-round second end 104e forreceiving a tool, not shown, adapted for use in removably threading themuffler body into passageway outlet end 28a, and an intermediateradially inwardly extending annular flange 104f. Muffler end cap 108 isof flexible plastic construction and formed adjacent its mouth with aplurality radially extending through openings 108a for use in snap-fitreceiving mounting tabs 104b' and adjacent its base with a plurality ofair exhaust openings 108b.

FIGS. 8-10 show an arrangement for collecting dust generated incident tooperation of sander 10 by use of a suitably remotely located source ofvacuum having a flexible hose connection 118. In this arrangement,conventional shroud 56 is replaced by dust collecting shroud 120 shapedto define a dust collecting chamber 120a having a downwardly facinginlet bounded by an annular lip 120b sized and arranged to extend freelyabout the periphery of sanding pad 54, and a chamber discharge port 120cbounded by an elongated discharge duct 120d; and a separately formedduct 122 is employed to connect discharge port 120c to hose connection118. Duct 122 is formed with a first end 122a sized to slidably receivedischarge duct 120b, a second end 122b having an annular rib 122c foruse in coupling the duct to hose connection 118, and an intermediatemounting portion in the form of a transversely extending mounting flange122d shaped to define a mounting opening 122e and a detent 122f.

As best shown in FIGS. 9 and 10, flange opening 122e is sized to freelyreceive first end 104a of muffler body 104, which when screwed intooutlet end 28a of air outlet passageway 28 effects clamping of mountingflange 122d between housing 12 and muffler body abutment flange 104c.Detent 122f is arranged for receipt within a housing recess 124 in orderto properly locate duct 122 relative to housing 12 and constrain theduct from rotation about an axis aligned with flange opening 122e.

Shroud 120 is preferably mold formed of resiliently deformable plasticmaterial such as will allow it to be snap-fit mounted on housing 12 inthe manner indicated in FIG. 9, and duct 122 is preferably mold formedof a relatively rigid plastic material to facilitate its connection todischarge duct 120d and hose connection 118 and its mounting on housing12. The illustrated mode of removably connecting duct 122 to hoseconnection 118 is conventional, and any suitable means may be employedin place thereof.

FIGS. 11-15 show an arrangement for collecting dust generated incidentto operation of sander 10 by making use of air discharged therefrom. Inthis arrangement, use may be made of previously described shroud 120,muffler body 104 and muffler cone 106 in combination with a uniquelydesigned aspirator 130 supplied with air discharged from sander 10through passageway 28.

Aspirator 130 generally includes a first portion 132 making use of airdischarged by sander 10 for creating a reduced pressure stream of airand a second portion 134 forming a flow passage for connecting dischargeport 120c of shroud 120 to such stream of air for purposes of drawingdust from the shroud. More specifically, first portion 132 includes anozzle 136 and a tubular member 138, which are removably, slidably fixedwithin opposite ends of a first part or tubular leg 140 of a generallyV-shaped, hollow housing 142 having a second part or tubular leg 144,which is disposed in flow communication with first part 140 and servesto define second portion 134. Housing first part 140 has a first ormounting end formed with an annular mounting flange 140a and apositioning detent 140b, and a second or discharge end formed with anannular rib 140c for use in coupling housing first part 140 to hoseconnection 118.

Nozzle 136 includes a generally tubular wall portion 146 having an openfirst or inlet end 146a sized to slidably receive end 104b of mufflerbody 104 and a second or discharge end 146b; and a generally concave,inclined flow directing wall portion 148, which joins with tubular wallportion 146 intermediate ends 146a and 146b and cooperates with end 146bto define a plurality of nozzle discharge apertures in the form ofarcuate slots 150. Slots 150 have their radially outer edges disposedessentially in alignment with the inner surface of tubular wall portion146, and are arranged to direct exhaust air in a direction extendingaxially of housing first part 140. Nozzle 136 is constrained againstrotation within housing first part 140 by means of a detent 146c, whichextends radially outwardly of tubular wall portion 14 and is slidablyreceived within a key slot 140d extending lengthwise of the innersurface of the housing first part.

Tubular member 138 defines an axially extending convergent/divergentflow passage 154 having a cylindrically shaped inlet end 156 arranged toreceive air exhausted from discharge slots 150, a convergent portion154a extending from inlet end 156 and a divergent portion 154b extendingfrom convergent portion 154a, as best shown in FIG. 12. Member 138 isdisposed within first part 140 for end abutting engagement with end 146bof nozzle side wall portion 146 and to position the cylindrical surface156a of its inlet end 156 in alignment with the radially outer edges ofdischarge slots 150, such that exhaust air discharged from such slotsflows parallel to and in engagement with a portion of the peripheralextent of surface 156a before entering the convergent portion 154a offlow passage 154. The stream of exhaust air defined by slots 150 and theportion of the peripheral extent of inlet end surface 156a with which itengages are of arcuate configuration when viewed in cross-section.

As viewed in FIG. 12, the concave outer surface 148a of wall portion 148is seen as converging towards the stream of exhaust air discharged fromslots 150 at an angle of about 135° and as being generally aligned withor following the contour of the inner surface of housing second part144, whereby these elements cooperate to direct dust laden air fromshroud exhaust port 120 into inlet end 156 of convergent/divergent flowpassage 154 at an angle relative to the axially extending stream ofreduced pressure air created by nozzle 136 and member 138. This anglemay be varied, but it must be greater than 90° and less than 180°.

Now referring to FIGS. 12-14, it will be apparent that member 138 isremovably snap-fit mounted within housing first part 140 by means of apair of resiliently deformable detents 140e, 140e formed integrally withthe housing first part and a pair of arcuate abutment surfaces 138a,138a, which extend radially between an outer guide surface 138b and apair of inner guide surfaces 138c, 138c of the member arranged adjacentinlet end 156 of its flow passage 154. One end of each inner guidesurface 138c is formed with an inclined cam surface 138d and adjacentends of the recesses are separated by a connecting portion of outerguide surface 138b, which is designated as 138e.

Detents 140e, 140e normally project radially inwardly of housing firstpart 140, such that they resiliently snap-fit into radial lappingengagement with abutment surfaces 138a, 138a, as an incident toinsertion of member 138 into housing first part 140, and thereafterlatch the member in inserted position. However, subsequent removal ofmember 138 may be effected by rotating the member in a counterclockwisedirection, as viewed in FIG. 13, sufficiently to move cam surfaces 138c,138c into underlying camming engagement with detents 140e, 140e in orderto force the latter to move outwardly of the inner surfaces 138c, 138cinto engagement with connecting portions 138e, 138e of member outerguide surface 138b, and thus free the member for withdrawal from housingfirst part 140.

Aspirator 130 is assembled by placing the O-ring seal 166 on mufflerbody 104 and then inserting the muffler body within housing first part140 and threading the muffler body into threaded outlet end 28a ofpassageway 28 sufficiently to effect clamping of housing first partmounting flange 140a between housing 12 and abutment flange 104c withhousing first part detent 140b being inserted into housing recess 124 toconstrain the aspirator from rotation relative to housing 12. Nozzle 136is then slidably inserted into the housing first part until it slidablyreceives muffler cap mounting end 104b and abuts against the O-ringseal. Thereafter, assembly is completed by slidably inserting member 138into housing first part 140 for abutting engagement with nozzle 136 toslightly compress O-ring seal 166 and to releasably latch detents 140e,140e against abutment surfaces 138c, 138c; slidably inserting dischargeduct 120d into housing second part 144; and connecting housing firstpart 140 to house connection 118. Inasmuch as the mode of mountingmember 138 permits its discharge end to project outwardly of housingfirst part 140, it is possible to connect the member directly to asuitable dust collector, not shown, as opposed to connecting the housingfirst part to a hose connection leading to a vacuum source.

Although having described the invention with specific reference to itsuse with an air powered random orbital sander, it will be appreciatedthat various aspects of the invention may be used in other tools.Moreover, the invention is not limited to air operated tools, and thus,the term air is meant to include any suitable pressurized gas. Stillfurther, it is contemplated that the motor mounting arrangement and flowcontrol valve of the present invention may be used in environments wherea pressurized liquid is employed in place of a compressible gas.

What is claimed is:
 1. A sander comprising in combination:a housingdefining a chamber having a side wall, an inner end and an open outerend, and an air supply and air exhaust passageways communicating withsaid chamber at points spaced annularly of said side wall intermediatesaid ends; an air motor disposed within said chamber and having a motorcasing and a rotor rotatably supported within said casing, said casinghaving opposite ends, a side wall and air inlet and exhaust ports spacedannularly of said side wall thereby and arranged intermediate saidopposite ends thereof; a sanding head; means for coupling said sandinghead to said rotor for imparting sanding movement to said sanding headin response to rotational movements of said rotor; and mounting meansfor non-rotatably mounting said casing within said chamber to arrangesaid air inlet and exhaust ports for flow communication with said airsupply and air discharge passageways, respectively, said mounting meansincluding resiliently deformable means having mounting portionsencircling said opposite ends of said casing and extending radiallybetween said side wall of said casing and said side wall of said chamberadjacent said inner and outer ends of said chamber and a pair ofintermediate sealing portions extending between said mounting portionsin engagement with said side walls of said chamber and said casing andbeing spaced apart annularly of said side wall of said casing to fluidseal said air inlet port and said air supply passageway from said airdischarge port and said air discharge passageway.
 2. A sander accordingto claim 1, wherein said mounting portions are separately formed andeach have a pair of sealing projections formed with free ends, the pairsof said sealing projections of said mounting portions having said freeends disposed in engagement and cooperating to define said pair ofintermediate sealing portions.
 3. A sander according to claim 1, whereina mounting pin extends from one of said ends of said motor casing forengagement with said housing to positionally locate said casing withinsaid chamber and arrange said air inlet and exhaust ports for flowcommunication with said air supply and air discharge passageways, saidmounting portions are separate end caps each having a pair of sealingprojections extending therefrom and terminating in free ends, one ofsaid end caps having an opening extending therethrough for receivingsaid mounting pin, and said free ends interengaging to locate the otherof said end caps relative to said one of said caps and prevent rotationtherebetween about an axis extending lengthwise of said casing.
 4. Asander according to claim 1, wherein said side wall of said casing iscylindrical and said side wall of said chamber is of frusto-conicalconfiguration with said outer end having a diameter greater than saidinner end.
 5. A sander according to claim wherein said sanderadditionally includes valve means having:a valve chamber defined by saidhousing and arranged to divide said air supply passageway into an inletflow path and an outlet flow path communicating with said valve chamber;a valve seat arranged in one of said inlet and outlet flow paths; avalve sleeve supported for rotation within said valve chamber and havinga through opening provided with opposite ends arranged for placing saidflow paths in flow communication; a valve member having sealing andoperating ends, said sealing end being arranged within said one of saidflow paths for removable engagement with said valve seat for selectivelyblocking and unblocking flow of air through said one of said flow paths,said operating end extending into said valve chamber from said one ofsaid flow paths and through one of said opposite ends of s id throughopening for receipt within said valve sleeve; an operator supported bysaid valve sleeve for engagement with said operating end of said valvemember within said through opening and being movable relative to saidvalve sleeve to effect movement of said valve member for removablyengaging said sealing end with said valve seat to selectively block andunblock flow of air through said one of said flow paths, said throughopening including said one of said opposite ends thereof being sized andshaped to permit said movement of said valve member and rotation of saidvalve sleeve within said valve chamber between first and second limits,and another of said opposite ends of said through opening cooperatingwith another of said flow paths to form a rotary valve for varying flowof air between said through opening and said other of said flow pathsincident to rotation of said valve sleeve between said limits.
 6. Asander according to claim 5, wherein said rotary valve provides for asubstantial linear variation in said flow of air incident to saidrotation of said valve sleeve.
 7. A sander according to claim 6, whereinan inlet end of said other of said flow paths is of a generally circularcross-sectional configuration and said other of said opposite ends ofsaid through opening has an essentially straight boundary edge inclinedrelative to the direction of said rotation of said valve sleeve betweensaid limits, said boundary edge cooperating with said inlet end of saidother of said flow paths to provide said variation incident to rotationof said valve sleeve.
 8. A sander according to claim 5, wherein springmeans is disposed within said one of said flow paths to normally biassaid sealing end of said valve member into engagement with said valveseat for blocking flow of air through said one of said flow paths.
 9. Asander according to claim 5, wherein said valve chamber and said valvesleeve have aligned end openings, and said operator is slidably androtatably supported by said end opening of said valve sleeve and has aninner end engaging with said operating end of said valve member and anouter end arranged to extend through said end opening of said valvechamber and be accessible from exteriorly of said housing.
 10. A sanderaccording to claim 5, wherein said valve chamber and said valve sleeveare of frusto-conical configuration.
 11. A sander according to claim 5,wherein said valve chamber has opposite ends opening exteriorly of saidhousing, said valve sleeve has one end thereof formed with an openingaligned with one of said opposite ends of said chamber for slidably androtatably supporting said operator, said operator has an inner endengaging with said operating end of said valve member and an outer endarranged to extend through said one of said opposite ends of saidchamber and be accessible from exteriorly of said housing, and saidvalve sleeve has another end thereof aligned with another of saidopposite ends of said valve chamber and is accessible from exteriorly ofsaid valve housing for imparting said rotation to said valve sleeve. 12.A sander according to claim 11, wherein said valve sleeve is insertableinto said valve chamber through said other of said opposite endsthereof, and latch means is provided to engage with said one end of saidvalve sleeve and said housing for removably retaining said valve sleevewithin said valve chamber, and said valve chamber and said valve sleeveare of frusto-conical configuration with said one of said opposite endsof said valve chamber and said one end of said valve sleeve being ofsmaller diameter than said other of said opposite ends of said valvechamber and said other end of said valve sleeve.
 13. A sander accordingto claim 1, wherein said sander additionally includes a shroud arrangedadjacent said sanding head for receiving dust generated incident tooperation thereof, said shroud having a discharge port from which dustmay be withdrawn; a duct for connecting said shroud discharge part to asource of vacuum and having a mounting portion; and a muffler connectedto said housing for receiving air discharged from said sander throughsaid air exhaust passageway, and said muffler mounting said mountingportion on said housing.
 14. A sander according to claim 13, whereinsaid mounting portion has an opening extending therethrough, saidmuffler removably mounts said mounting portion on said tool with saidopening in alignment with said exhaust passageway and said muffler, andsaid mounting portion and said housing have removable engaging means forconstraining rotation of said mounting portion about an axis alignedwith said opening.
 15. A sander according to claim 13, wherein saidshroud has an integrally formed discharge duct bounding said dischargeport, said duct is removably connected to said discharge duct, saidmounting portion is a mounting flange having an opening extendingtherethrough and a detent, said muffler removably clamps said mountingflange against said housing with said opening in alignment with saidexhaust passageway, and said housing includes means removably engagingwith said detent for constraining rotation of said mounting flangerelative to said housing about an axis aligned with said opening.
 16. Asander according to claim 1, wherein said sander additionally includes:ashroud arranged adjacent said sanding head for receiving dust generatedincident to operation thereof, said shroud having a dust discharge portthrough which dust may be withdrawn, and an aspirator for withdrawingdust through said dust discharge port, said aspirator having a firstportion connected to said exhaust passageway for creating a reducedpressure stream of air from air exhausted from said housing through saidexhaust passageway and a second portion for connecting said dustdischarge port to said reduced pressure stream for drawing dust fromsaid shroud.
 17. A sander according to claim 16, wherein said firstportion includes a nozzle means arranged to receive air from saidexhaust passageway and to direct air exhausted from said nozzle meansfor flow in a given direction and means defining a convergent/divergentthrough flow passage arranged in alignment with said given direction andhaving an inlet end arranged to receive said air exhausted from saidnozzle means, a convergent portion extending from said inlet end and adivergent portion extending from said convergent portion, and said airexhausted from said nozzle means is directed to enter said flow passageonly adjacent a portion of the peripheral extent of said inlet endthereof, and said second portion connects said dust discharge port tosaid inlet end.
 18. A sander according to claim 17, wherein said airexhausted from said nozzle means and said portion of said peripheralextent of said inlet end of said flow passage are of arcuateconfiguration when viewed in cross-section.
 19. A sander according toclaim 18, wherein a dust flow directing surface converges towards saidstream of air in said given direction and towards said inlet end.
 20. Asander according to claim 19, wherein said dust flow directing surfaceis concave when viewed in cross-section.
 21. A sander according to claim20, wherein said second portion includes a dust discharge flow passagepositioned to cooperate with said dust flow directing surface to directdust into said inlet end of said flow passage in a direction forming anangle of greater than 90° and less than 180° relative to said givendirection.
 22. A sander according to claim 1, wherein said sanderadditionally includes:a shroud arranged adjacent said sanding head forreceiving dust generated incident to operation of said sanding head,said shroud having a dust discharge port through which dust may bewithdrawn; a nozzle communicating with said air exhaust passageway fordischarging exhaust air in a given direction; means having aconvergent/divergent through passage, said through passage having aninlet end arranged adjacent said nozzle for receiving said exhaust airwith said exhaust air being directed to engage with only a portion ofthe periphery of a surface of said through passage bounding said inletend, a convergent portion extending from said inlet end and a divergentportion extending from said convergent portion; and flow passage meanscommunicating at opposite ends thereof with said dust discharge port andsaid inlet end.
 23. A sander according to claim 22, wherein said portionof the periphery of a surface of said through passage and said exhaustair as discharged from said nozzle have generally arcuatecross-sectional configurations.
 24. A sander according to claim 22,wherein a flow directing surface is arranged to converge towards saidexhaust air discharged from said nozzle in a said given direction, andsaid flow directing surface cooperates with said flow passage means todirect dust into said inlet end.
 25. A sander according to claim 24,wherein said portion of the periphery of a surface of said throughpassage and said exhaust air discharged from said nozzle have generallyarcuate cross-sectional configurations and said flow direction surfacehas a concave cross-sectional configuration.
 26. A sander according toclaim 25, wherein said nozzle is removably attached to said housing andsaid flow passage means is removably attached to said shroud.